1. Field of the Invention
The present invention relates generally to the field of semiconductor manufacturing. More specifically, the present invention relates to a tungsten chamber with a stationary heater useful, for example, in chemical vapor deposition processes.
2. Description of the Related Art
Chemical vapor deposition (CVD) is one of a number of processes used to deposit thin films of material on semiconductor substrates. To process substrates using CVD, a vacuum chamber is provided with a susceptor configured to receive a substrate. In a typical CVD chamber, the substrate is placed into and removed from the chamber by a robot blade and is supported by the susceptor during processing. A precursor gas is charged to the vacuum chamber through a gas manifold plate situated above the substrate, where the substrate is heated to process temperatures, generally in the range of about 250xc2x0-650xc2x0 C. The precursor gas reacts on the heated substrate surface to deposit a thin layer thereon and to form volatile by-product gases, which are pumped away through the chamber exhaust system.
One cause of particulate contamination in the chamber is deposition of material at the edge or on the backside of the substrate. Substrate edges are typically beveled, making deposition difficult to control over these surfaces and deposition at substrate edges can be, therefore, non-uniform. This may lead to deposited layers that do not adhere properly to the substrate edge and eventually chip or flake off, causing unwanted particle generation in the chamber. Additionally, chemical mechanical polishing is often used to smooth the surface of a substrate coated with tungsten or other metals. The act of polishing will cause any deposits on the edge and backside surfaces to flake off and generate unwanted particles.
Different approaches have been employed to control the deposition of process gases on the edge of a substrate during processing. One approach employs a shadow ring that essentially masks a portion of the perimeter of the substrate from the process gases. However, this method reduces the overall useful surface area of the substrate and in light of the current demand from chip manufacturers for zero edge exclusion, this method is becoming impractical.
Another approach to control the deposition of process gases on the edge of a substrate employs a gas manifold near the edge of the substrate for the delivery of purge gas past the edge to prevent edge deposition on the substrate. The purge gas inhibits the deposition of process gases at the substrate edge, but the purge gas also mixes with the process gas and is typically exhausted through the same manifold as the process gas. This mixing can lead to dilution of the process gas and/or non-uniform deposition of the gases on the substrate surface. A third approach uses a shadow ring and a purge gas channel in combination to form a purge gas chamber adjacent to the substrate edge having a purge gas inlet and outlet. This system requires a higher pressure within the purge gas chamber than in the process chamber to keep the process gas from being drawn into the purge gas outlet. Therefore, the purge gas is drawn into the chamber and out through the processing chamber exhaust system. Drawing the purge gas into the exhaust system of the process chamber can have a negative effect on the process uniformity over the substrate surface.
The prior art is deficient in the lack of an effective device and/or means that allows for full surface coverage of a substrate so as to prevent backside and edge deposition without disrupting the uniformity of the process gases and the resulting uniformity of the film formed on the substrate. Specifically, the prior art is deficient in the lack of effective devices/means to separate the processing compartment from the purge compartment in a vacuum chamber and therefore avoid the mixing of the process gas and purge gas, and prevent substrate backside and edge deposition. The present invention fulfills these long-standing needs and desires in the art.
In one aspect, there is provided a chamber for depositing a film on a substrate for semiconductor manufacturing, comprising a process compartment; a purge compartment; a purge ring located on the chamber body to separate the process compartment from the purge compartment; a heater; and a shadow ring. The shadow ring covers the periphery of the substrate.
In another aspect, there is provided a method for depositing a film of uniformity on a substrate in a chamber. This method comprises the following steps: (1) positioning the substrate on a substrate receiving surface of a substrate support member in a process compartment. The periphery of the substrate is covered by a shadow ring; (2) flowing a process gas into the process compartment and to the non-covered areas of the substrate; (3) flowing a purge gas through a purge gas channel positioned in a purge compartment. The purge compartment is separated from the process compartment by a purge ring; and (4) exhausting the process and purge gas from the chamber through a pumping channel formed in the chamber body. As a result, a uniform film is deposited on the substrate in the chamber.
Other and further aspects, features, and advantages of the present invention will be apparent from the following description of the embodiments of the invention given for the purpose of disclosure.